Conventional busway power distribution systems supply electrical energy for commercial, residential, and industrial purposes. Busway systems are generally comprised of several factory-assembled sections, each of which includes a number of individually insulated, generally flat, elongated electrical conductors (more commonly known as “busbars”). The busbars are typically stacked one upon another and enclosed within a housing (or “protective duct”), which is intended to provide protection and support for the busbars. In many designs, the housing includes a duct top and a duct bottom, which cover the flat top- and bottom-surfaces of the busbars, respectively, and two or more duct sides of one or more panels each, which cover the lateral edges of the busbars. The duct tops and bottoms of the housing can be made of electrically conductive materials, such as aluminum or copper, for carrying the system ground current. The duct sides are generally made of a structurally robust material, such as steel, that is formed to provide strength to the housing. The housing is generally held together by rivets, screws, bolts, stitching, or other known methods.
During a short circuit event, magnetic repulsion forces can be generated between the individual busbars, urging the busbars away from each other, which can cause the busbars to deform which, in turn, causes the housing to bulge. In extreme cases, large short circuits can cause the housing to be pulled apart. To prevent or limit such damage, surge clamps are placed across the duct tops and bottoms at each end of the busway section and, often, at predetermined intervals along the longitudinal length of the busway section. The surge clamps are generally U-shaped in cross-section with flanges closing the ends. Existing surge clamps are bolted or otherwise rigidly fastened to the sides of the housing. The surge clamps are designed to mitigate the forces and vibrations caused by the short-circuit current by supporting the busbars at intervals to thereby maintain the busbars in proper relationship to each other and to the enclosures of the busbars.
Most surge clamps are rigidly fastened to the duct sides, for example, by screws or bolts that pass through the duct side and into the surge clamp end flanges. In many current designs, the surge clamps merely act to retain the busbars within the duct housing, and do not apply a compressive force to the busbar stack. Due to inherent manufacturing variations and build tolerances caused during assembly of the clamps and busway section, one or more of the surge clamps may not properly contact the top/bottom of the housing leaving gaps therebetween. These inadvertent gaps between the top/bottom of the housing and the surge clamp allow the conductor bars to separate in a short circuit event and, in some cases, permanently deform and damage the housing. The deformation of the busbars through the gaps also create an impact load when the busbars finally contact the surge clamps, increasing the stress that the surge clamps must endure. In addition, inadvertent gaps between the various components of the busway create internal air pockets, which impair thermal dissipation of heat generated by the system's electrical resistivity. There is therefore a need for clamping devices that more effectively maintain the busbars in proper relationship to each other and to the duct housing. There is also a need for clamping devices that eliminate unintentional gaps between the surge clamp and the housing.